I onic Compounds and Ionic Bonding

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Ionic Compoundsand

Ionic Bonding

Chemical Bonds

Ionic - The electrostatic attraction between ions

Covalent - The sharing of electrons between atoms

Metallic - Each metal atom bonds to other metals atoms within a "sea" of electrons (covered in a later unit)

There are three basic types of bonds:

Periodic Table - Review

The periodic table is "periodic" because of certain trends that are seen in the elements.

Properties of elements are functions of their atomic number.

Elements from the same family/group have similar physical and chemical properties.

Atoms are listed on the periodic table in rows, based on number of protons, which is equal to the number of electrons in a neutral atom.

The Periodic Table of the Elements

The periodic table can be also divided into metals (left/blue) and nonmetals (right/yellow).

A few elements retain some of the properties of metals and nonmetals, they are called metalloids (staircase/pink).

1 In the periodic table, the elements are arranged in __________.

A alphabetical order

B order of increasing atomic number

C order of increasing metallic properties

D order of increasing neutron content

E reverse alphabetical order

F I don't know how to answer this.

2 Elements __________ exhibit similar physical and chemical properties.

A with similar chemical symbols

B with similar atomic masses

C in the same period of the periodic table

D on opposite sides of the periodic table

E in the same group of the periodic table

3 Which pair of elements would you expect to exhibit the greatest similarity in their physical and chemical properties?

A H, Li

B Cs, Ba

C Ca, Si

D Ga, Ge

E C, O

4 Which one of the following is a nonmetal?

5 Potassium is a __________ and chlorine is a __________.

A metal, nonmetal

B metal, metal

C metal, metalloid

D metalloid, nonmetal

E nonmetal, metal

Atoms tend towards having complete outer shells of electrons (remember stability).

A full outer shell will have: 2 electrons in the s subshell and 6 electrons in the p subshell ( s2p6 configuration)

Octet rule: atoms tend towards having a total of 8 electrons 8 valence electrons make an octet

Review: Octet Rule

Valence Electrons

Valence electrons are the electrons in the highest occupied energy level of an element’s atoms.

The number of valence electrons largely determines the chemical properties of an element.

Atoms in group 3 have 3 valence electrons, atoms in group 17 have 7 valence electrons, etc.

Valenceelectron

To find the number of valence electrons in an atom of a representative element, simply look at its group number.

Valence Electrons

1 2 3 4 5 6 7 8

There is one exception: helium has only 2 valence electrons.

Number of valence electrons in neutral atoms:

6 How many valence electrons does Aluminum have?

E I don't know how to answer this.

7 How many valence electrons does Barium have?

Cations are positive and are formed by elements on the left side of the periodic chart (metals).

Anions are negative and are formed by elements on the right

side of the periodic chart (nonmetals).

The Formation of Cations

Metals usually give up valence electrons

This results in a noble gas (8 electron) outer shell.

The configuration of the Sodium ion is the same as Neon

Na : 1s2 2s2 2p6 3s1 Na+1 : 1s2 2s2 2p6

Loss of valence electrons

Ne atom

Na atom Na+ ion

loses e-

11p11e-

11p10e-

Cations of Group 1A elements always have a charge of 1+.

Cations of Group 2A elements always have a charge of 2+.

Mg Mg2+ 2e-+

Magnesium atom(electrically

neutral, charge = 0)

Magnesium ion(+2 indicates 2 units of

positive charge)

(2 in front of e- indicates 2 units of negative charge)

Nonmetals usually gain valence electrons.

This results in a noble gas (8 electrons) outer shell

The Formation of Anions

A chloride ion has the same electron configuration as argon.

Cl: 1s2 2s2 2p6 3s2 3p5 Cl- 1s2, 2s2, 2p6, 3s2, 3p6 Ar atom

Cl atomCl- ion

Gains an e-17P17e- 17p

Anions of Group 15 (5A) elements have a charge of 3-

Anions of Group 16 (6A) elements always have a charge of 2-

Anions of Group 17 (7A) elements have a charge of 1-

8 Metals tend to __________ electrons and cations tend to __________ electrons.

A gain, gain

B lose, lose

C gain, lose

D lose, gain

E neither, they keep their electrons

9 Anions tend to be __________ and cations tend to be __________.

A metals, metals

B nonmetals, nonmetals

C metals, nonmetals

D nonmetals, metals

E metalloids, metalloids

10 Metals lose electrons to form cations

TrueFalse

11 Anions are formed from nonmetals

TrueFalse

12 Nonmetals tend to lose electrons forming ions

13 This is the ion formed from a calcium atom

B Ca2+

D Ca2-

14 Barium forms an ion with a charge of __________.

15 Aluminum forms an ion with a charge of __________.

16 Of the following, __________ contains the greatest number of electrons.

17 Oxygen forms an ion with a charge of __________.

18 Iodine forms an ion with a charge of __________.

19 This is the ion formed from nitrogen

20 Predict the charge of the most stable ion of S?

Electronegativity is how strongly an atom attracts electrons. Atoms with a high electronegativity will be able to attract electrons away from atoms with a much lower electronegativity.

This removal of electrons can occur when the difference in electronegativity between the two atoms is approximately 1.7 or higher.

Once a positive and negative ion are formed, they will be attracted to each other via the electrostatic force: 

Ionic Bonding

F = k q1 q2

  Note: The heavier nonmetals from

4,6,5th groups( In, Tl, Sn, Pb, Sb Bi )

may act like metals

An electronegativity difference of approximately 1.7 can only occur between a metal and a nonmetal.

Ionic Bonding

21 Which pair of atoms will form an ionic bond?

A Li and Ne

B K and Br

C K and Cs

D S and Cl

22 Which pair of atoms will form an ionic bond?

A Li and BeB Na and Mg

C K and Ca

D Na and Cl

23 Which of the following compounds would you expect to be ionic?

C SrCl2

Formation of Ionic Compounds

Compounds composed of cations and anions are called ionic compounds.

Although they are composed of ions, ionic compounds are electrically neutral.

The electrostatic forces that hold ions together in ionic compounds are called ionic bonds.

When sodium and chlorine are close together, sodium's valence electron flies off and "harpoons" the chlorine atom.

The result is a sodium cation (+) next to a chloride anion (-)

These oppositely charged two ions attract: they reel one another together to form an ionic bond.

Ionic Bonds

1s2 2s2 2s2 2p6 3s1 1s2 2s2 2p6 3s2 3p5 1s2 2s2 2p6 1s2 2s2 2p6 3s2 3p6

Na Cl Na+ Cl-

1s2 2s2 2p6 1s2 2s2 2p6 3s2 3p6

Ionic Bonds

The electron transfer process in creating an ionic bond:

The dots represents the valence electrons in an atom.

click here for an animation of this reaction

A chemical formula shows the kinds and numbers of atoms in the smallest representative unit of a substance.

A formula unit is the lowest whole-number ratio of ions in an ionic compound.

Every ionic compound has a 3D array of positive and negative ions.

Formula Units

Properties of Ionic Compounds

They are crystalline solids at room temperatureThey have high melting pointsThey conduct electricity when melted (molten) or dissolved in water (aqueous)

Ionic bond Nomenclature

Writing ionic compounds

Criss-Cross Rule

1. Main Group metals

Alkali (1)Alkali earth (2)Group 13 (3A)

Example: Aluminum Chloride

Step 1:

Step 2:

Step 3: AlCl3

Criss-Cross Rule

3+ 1-write symbols & charge of elements on top

(charges based on group numbers)

criss-cross charges as subscripts

combine as formula unit(“1” is never shown)

Aluminum Chloride

Example: Aluminum Chloride

Step 1: Aluminum Chloride

Step 2: Al3+ Cl1-

Step 3: Al Cl1 3

AlCl 3

Criss-Cross Rule

Example: Aluminum Oxide

Step 1: Aluminum Oxide

Step 2: Al3+ O2-

Step 3: Al O2 3

Criss-Cross Rule

2. Transitional metals

SilverIron IIZinc

Example: Chromium ChlorideStep 1:

Step 2:

Step 3: CrCl4

Criss-Cross Rule

4+ 1-write symbols & charge of elements on top

(charges given by name)

criss-cross charges as subscripts

combine as formula unit(“1” is never shown)

Chromium (IV) Chloride

Transitional metals exception

Ag = +1Zn = +2

Steps in Naming

1. Determine if its ionic2. Is it a main group metal or transition

– Does it have a metal in it

Steps in Naming

1. Determine if its ionicDoes it have a metal in it

2. Is it a main group metal or transition

(Ionic) CompoundsAll have metals in them2 types of ionic compounds

Main group – 1A, , 2A, 3 - 13ATransitional - 3B -12B

Naming Ionic Compounds

Main group metals.

To name these compounds, give the name of metal followed by thename of the non-metal, with the ending replaced by the suffix –ide.

Examples:

NaCl sodium chloride (Na1+ Cl1-)

CaS calcium sulfide (Ca2+ S2-)

AlI3 aluminum iodide (Al3+ I1-)

Ionic Compounds IIContaining a transition Metal

1. Give the name of the metal followed by Roman numerals in parentheses to indicate the oxidation number or charge

2. Give the name of the nonmetal, with its ending replaced by the suffix –ide.

Examples

• Fe (II) Oxide• Sn (IV) Oxide

The roman numeral is based on the charge of a single metal atom!

Procedures to write their names

1. Write the symbols for cation and anion2. Find the total charge for the anion, write it

on top of the anion (charge X # of atoms)3. Write the opposite charge on top of cation4. Show the number of atoms for cation5. Calculate the charge each metalic cation

should have.6. Write the metal with correct roman numeral

based on a single cation and the anion

Example = Cr2O3

Step 1 Write the symbol for the elements and number of atoms for cation and anion

Cr2 O3

Example = Cr2O3

Step 2 :Find the total charge for the anion

a. Multiply charge on a single ion by its subscript

A single O anion has a -2 charge it has 3 atoms so total charge is -6

Step 3 Write the opposite charge on top of cation

• Cr2 +6

Example = Cr2O3

Step 4 Show the number of atoms for cation

• Cr2 O3

Example = Cr2O3

Step 5 Calculate the charge each metallic cation should have

• Cr2 O3

Example = Cr2O3

Step 6 Write the metal with correct roman numeral based on a single cation and the anion

• Cr2 O3

Answer = chromium (III) oxide

Based on a single atom

Examples: Transition metals

Formula Name

1 Hg2O2 HgO3 Fe2O3

31 The formula for barium sulfide is Ba2S2.

Polyatomic Ionsor Ternary Ionic Compounds

Gang Up and Charge

Polyatomic Ions

• Charged particles made of more than one kind of atom.

• Atoms are held together with covalent bonds. • Each has its own name, based on the atoms it

contains. Many chemists memorize these names. We will use a list.

Cyanide Ion

Common Polyatomic Ions

Names of Common Polyatomic Ions

Ion Name Ion Name

NH4 1+ ammonium CO3 2- carbonate

NO2 1- nitrite HCO3 1- hydrogen carbonate NO3 1- nitrate (“bicarbonate” is a widely SO3 2- sulfite used common name) SO4 2- sulfate ClO 1- hypochlorite HSO4 1- hydrogen sulfate ClO2 1- chlorite

(“bisulfate” is a widely ClO3 1- chlorate used common name) ClO4 1- perchlorate OH 1- hydroxide C2H3O2 2- acetate CN 1- cyanide MnO4 1- permanganate PO4 3- phosphate Cr2O7 2- dichromate HPO4 2- hydrogen phosphate CrO4 2- chromate H2PO4 1- dihydrogen phosphate O2 2- peroxide

Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 100

CO3-2 carbonate This ion is composed of one carbon and three oxygens and the

entire group has a charge of -2.

Polyatomic ion – Group of atoms that act as a unit and carry a charge.

More examples:

SO4-2 Sulfate

SO3-2 Sulfite

ClO4-1 Perchlorate

ClO3-1 Chlorate

ClO2-1 Chlorite

ClO-1 Hypochlorite

PO4-3 Phosphate

C2H3O2-1 Acetate

OH-1 Hydroxide

NO3-1 Nitrate

NO2-1 Nitrite

You need to learn these!!!

NH4+1 Ammonium

(only positive PI)

How do you recognize Ternary Ionic Compounds?

Composed of two ions in which at least one is a polyatomic ion.

There is only one positive polyatomic ion (NH4+1)

Three possible types of Ternary Ionic Compounds:•Ammonium + negative ion (nonmetal)•Metal (positive ion) + negative polyatomic ion•Ammonium + negative polyatomic ion

How do you name Ternary Ionic Compounds?

EASY! PIECE OF CAKE! NO PROBLEM!

Name the first ion.

Name the second ion. Isn’t that simple??!!

Examples:

Na2CO3

When you look at this compound you should recognize that this is NOT binary. There are THREE elements present. When you see this, immediately look for a polyatomic ion. Carbonate is present here.

Name the first ion.

Sodium

Name the second ion.

carbonate

Notice that you do NOT change the suffix – just name the polyatomic ion

How do you write formulas for Ternary Ionic Compounds?

Very much like writing formulas for Binary Ionic Compounds.

Two steps:•Write the formulas/symbols of each ion.•Balance the charges by supplying subscripts.• If a subscript is needed for a polyatomic ion, it must be put in parentheses with the subscript on the outside.

Let’s do some!!

Magnesium Phosphate

Step 1: Magnesium Phosphate

Step 2: Mg2+ PO43-

Step 3: Mg (PO4)3 2

Step 4: Mg3(PO4)2

polyatomic Compounds

1. ________________ calcium phosphate

2. ________________ ammonium carbonate

3. ________________ aluminum sulfate

4. Na2SO4 ____________________

5. LiCN ____________________

6. Ba(ClO3)2 ____________________

7. ________________ copper (II) hydroxide

Ca3(PO4) 2

(NH4)2CO3

Al2(SO4)3

sodium sulfate

lithium cyanide

barium chlorate

Cu(OH)2

43 The formula for sodium hydroxide is

A Na (OH)2

B Na(OH)

C Na(OH2)

D Na(HO)

44 The formula for aluminum phosphate is:

A Al(PO4 )

B Al3(PO4)

C Al2(PO4)3

D Al3(PO4)3

47 NaClO is

A sodium chlorate

B sodium chloride

C sodium chloriteD sodium hypochlorite

49 Ammonium carbonate is

A (NH4)(CO3)

B (NH4)2(CO3)

C (NH4)(CO3)2

D (NH4)2(CO2)

PRACTICEWriting Formulas for Ionic Compounds

Complete the table by filling in the formula for the ionic compound formed by each pair of cations and anions, as shown for the first pair.

Write the formula for the following compounds:

1. Magnesium iodide

2. Calcium sulfite

3. Barium hydrogen carbonate

4. Iron (III) phosphate

PRACTICEWriting Formulas for Ionic Compounds

I onic Compounds and Ionic Bonding

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